Cooking a 20-pound turkey usually takes about 4 to 4.5 hours at 325°F (165°C) for an unstuffed turkey. If it's stuffed, it might take a bit longer, around 4.5 to 5 hours. It's important to use a meat thermometer to ensure it's fully cooked—the internal temperature should reach 165°F (74°C) in the thickest part. Are you planning a big gathering, or is it a cozy dinner? I’d love to hear how your meal is coming together!